WO 2008/113752 A1 discloses a gas flow reversing element which allows a human being to be ventilated by way of a relatively thin catheter, for example in emergency situations. Oxygen can thus be introduced into the lung and gas can also be aspirated from the lung again in sufficient quantity. The high flow rate in both directions, despite the small diameter of the catheter, is able to maintain the supply of oxygen and the removal of carbon dioxide when ventilating through a relatively thin catheter.
Various devices for transtracheal ventilation are known from the article “Comparison of four different emergency airway access equipment sets on a human patient simulator” in Anaesthesia, 2004, 59, pages 73-79, in particular from FIG. 4, which shows an easy to use device for jet ventilation.
The main aim of the present invention is to extend the field of use of jet ventilation, to make it safer, and to create suitable devices and methods therefor. With classical jet ventilation, a mixture of oxygen and air is blown with a high pressure and flow via a katheter into the airway and used or excessive gas can escape via the airway. In contrast hereto, the concept of the present invention can be described as jet ventilation with expiratory assistance, which can also be used when this escape is not possible or is possible only with difficulty.
Surprisingly, the ventilation method hitherto conceived for emergency care in cases of partially or completely obstructed airways is also suitable for other uses. Hitherto, in operations performed in the region of the lower airways and the lungs, catheters with relatively large diameters have been used for ventilation purposes and for introducing instruments, but these restrict the possibilities of performing treatment alongside the catheter or of introducing additional catheters and instruments.
An additional and often underestimated problem is that, when a high concentration of oxygen is present in the airways and use is being made of a laser, for example, or of other instruments that generate high temperatures, there is a risk of burning. This concerns the surrounding tissue, but also the catheter and the instruments themselves.
An important aspect of jet ventilation is the safety of the patient during its use. In conventional jet ventilation systems, there is a danger that, if the airways are substantially or completely obstructed, too high a pressure will build up in the lung. Consequently, the field of use has hitherto been limited.
The object of the present invention is therefore to make available devices and methods which, in particular during an examination or operation, permit safe ventilation of a patient by means of jet ventilation with expiratory assistance and leave considerable parts of the cross-sectional area of the upper airways free for necessary interventions.